1. Field of the Invention
This invention relates to generating visual displays of spatially related material, such as for instance schematic diagrams and flow charts, on electronic display devices such as cathode ray tubes, and more particularly to magnifying portions of such displays without changing the boundaries of the total viewiwng area and without losing the spatial relationship between the material that is magnified and the remaining material.
2. Prior Art
The display of large area illustrations on limited area devices such as cathode ray tubes poses the dilemma of having to choose between total area display at reduced magnification or only partial area displays at normal or increased magnification. An example of this predicament is the display of schematic diagrams or flow charts where it is desired to see the overall layout and structure and, on the same display, have sufficient magnification to see local detail and annotation.
The conventional solution to this problem is to have separate displays of different magnifications, and an observer must then switch between displays to satisfy the need for both detailed information and overall structure and context. This solution is not only aggravating but requires the observer to remember information from one display while using another. When the needed information extends over several partial area displays of normal magnification, the observer's work load and memory requirements can be such that the displays become unusable.
It is a primary object of the invention to magnify selected portions of an image presented in a display area of fixed dimensions without eliminating any material from the image.
It is also an object of the invention to achieve the above object while maintaining the indicated relationships between material in the magnified areas and that in the other areas.